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10 results on '"European Project: 766726,211587,COSMICS(2017)"'

1. Voltage-Induced Bistability of Single Spin-Crossover Molecules in a Two-Dimensional Monolayer

Author

Marie-Laure Boillot, Jérôme Lagoute, Kaushik Bairagi, Massine Kelai, Amandine Bellec, Vincent Repain, Yongfeng Tong, Yann Girard, Sylvie Rousset, Talal Mallah, Cristian Enachescu, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Institut de Chimie du CNRS (INC)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Alexandru Ioan Cuza University of Iași [Romania], and European Project: 766726,211587,COSMICS(2017)

Subjects
Materials science, Spintronics, Spin states, Bistability, Relaxation (NMR), [CHIM.MATE]Chemical Sciences/Material chemistry, Molecular physics, law.invention, Spin crossover, law, Monolayer, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, Physical and Theoretical Chemistry, Scanning tunneling microscope, Spin-½
Abstract

International audience; Bistable spin-crossover molecules are particularly interesting for the development of innovative electronic and spintronic devices as they present two spin states that can be controlled by external stimuli. In this paper, we report the voltage-induced switching of the high spin/low spin electronic states of spin-crossover molecules self-assembled in dense 2D networks on Au(111) and Cu(111) by scanning tunneling microscopy at low temperature. On Au(111), voltage pulses lead to the nonlocal switching of the molecules from any─high or low─spin state to the other followed by a spontaneous relaxation toward their initial state within minutes. On the other hand, on Cu(111), single molecules can be addressed at will. They retain their new electronic configuration after a voltage pulse. The memory effect demonstrated on Cu(111) is due to an interplay between long-range intermolecular interaction and molecule/substrate coupling as confirmed by mechanoelastic simulations.

Published
2021
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2. Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface

Author

Cristian Enachescu, Yann Girard, Massine Kelai, Philippe Sainctavit, Marie-Laure Boillot, M.-A. Arrio, Arthur Tauzin, Jérôme Lagoute, Sylvie Rousset, Edwige Otero, Talal Mallah, Weibin Li, Vincent Repain, Amandine Bellec, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Institut de Chimie du CNRS (INC)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Alexandru Ioan Cuza University of Iasi, University of Iasi, Grant of the Romanian ministry of research, Innovation and Digitization, CNCS/CCCDI-UEFISCDI, project N° PN-III-P4-ID-PCE-2020-1946, European Project: 766726,211587,COSMICS(2017), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and SOLEIL Synchrotron, L'Orme des Merisiers, 91198 Gif-sur-Yvette, France

Subjects
Materials science, Absorption spectroscopy, Bistability, 02 engineering and technology, Substrate (electronics), [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Condensed Matter::Materials Science, symbols.namesake, Thermal Bistability, Spin crossover, Monolayer, General Materials Science, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS, Arrhenius equation, Substrate Interaction, Spintronics, Mechanoelastic Model, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, X-ray Absorption Spectroscopy, Spin-Crossover, Chemical physics, symbols, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology
Abstract

Spin-crossover molecules are very attractive compounds to realize multifunctional spintronic devices. Understanding their properties when deposited on metals is therefore crucial for their future rational implementation as ultrathin films in such devices. Using X-ray absorption spectroscopy, we study the thermal transition of the spin-crossover compound FeII((3,5-(CH3)2Pz)3BH)2 from submonolayer to multilayers on a Cu(111) substrate. We determine how the residual fraction of high spin molecules at low temperature, as well as the bistability range and the temperature of switching, depends on the layer thickness. The most spectacular effect is the clear opening of a 35 ± 9 K thermal hysteresis loop for a 3.0 ± 0.7 monolayers thick film. To better understand the role played by the substrate and the dimensionality on the thermal bistability, we have performed Monte Carlo Arrhenius simulations in the framework of a mechanoelastic model that include a molecule-substrate interaction. This model reproduces well the main features observed experimentally and can predict how the spin-crossover transition is modified by the thickness and the substrate interaction.

Published
2021
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3. Magnetic properties of devicelike cobalt/2D materials interfaces

Author

M. Belmeguenai, Cyrille Barreteau, Yves Roussigné, Jacko Rastikian, Stéphan Suffit, Amandine Bellec, Clément Barraud, Vincent Repain, Ludovic Le Laurent, S. M. Chérif, Samir Farhat, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire des Sciences des Procédés et des Matériaux (LSPM), Institut Galilée-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Nord, Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), European Project: 766726,211587,COSMICS(2017), and Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
Materials science, Physics and Astronomy (miscellaneous), Spintronics, Condensed matter physics, Magnetism, Graphene, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, Brillouin zone, Condensed Matter::Materials Science, chemistry, Ab initio quantum chemistry methods, law, Physical vapor deposition, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, 010306 general physics, 0210 nano-technology, Cobalt, Single crystal, ComputingMilieux_MISCELLANEOUS
Abstract

We have studied the magnetism of a cobalt ultrathin film deposited on different two-dimensional (2D) materials, namely graphene, h-BN, and ${\mathrm{WSe}}_{2}$ by the Brillouin light scattering technique. The studied samples are prepared by a pick-up method of large flakes deposited on ${\mathrm{SiO}}_{2}$ and the subsequent physical vapor deposition of metal layers, in a similar way to what is done to make spintronic devices out of such materials. Compared to the reference layer $(\mathrm{Co}/{\mathrm{SiO}}_{2})$, the perpendicular magnetic anisotropy is enhanced in the Co/2D systems, although less than what could be expected on single crystal samples. This result is quantitatively discussed by comparison with ab initio calculations in the case of the Co/graphene interface. We also measure an increase of the magnetic damping and a small Dzyaloshinskii-Moriya interaction in such samples which are discussed with respect to the recent literature.

Published
2021
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4. Reversible coordination-induced spin-state switching in complexes on metal surfaces

Author

Edwige Otero, Felix Tuczek, Alexander Köbke, Alexander Weismann, Kai Rossnagel, Sebastian Rohlf, Sven Johannsen, Manuel Gruber, Torben Jasper-Toennies, Richard Berndt, Michał Studniarek, Rainer Herges, Philippe Ohresser, Florian Gutzeit, Christian Näther, Florian Diekmann, Fadi Choueikani, Danilo Longo, Fynn Röhricht, Alexander Schlimm, Jan Grunwald, Institut für Experimentelle und Angewandte Physik [Kiel] (IEAP), Christian-Albrechts-Universität zu Kiel (CAU), Otto-Diels-Institut für Organische Chemie, Paul Scherrer Institute (PSI), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Christian-Albrechts University of Kiel, COSMICS, European Project: 766726,211587,COSMICS(2017), Institut fur Anorganische Chemie, The Swiss Light Source (SLS) (SLS-PSI), and Deutsches Elektronen-Synchrotron [Hamburg] (DESY)

Subjects
Materials science, Spin states, Biomedical Engineering, Bioengineering, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Metal, chemistry.chemical_compound, Molecule, General Materials Science, Electrical and Electronic Engineering, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], [PHYS]Physics [physics], Spin polarization, Spintronics, Ligand, [CHIM.ORGA]Chemical Sciences/Organic chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Porphyrin, Atomic and Molecular Physics, and Optics, 3. Good health, 0104 chemical sciences, chemistry, Chemical physics, Intramolecular force, visual_art, visual_art.visual_art_medium, Condensed Matter::Strongly Correlated Electrons, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, ddc:600
Abstract

Molecular spin switches are attractive candidates for controlling the spin polarization developing at the interface between molecules and magnetic metal surfaces1,2, which is relevant for molecular spintronics devices3–5. However, so far, intrinsic spin switches such as spin-crossover complexes have suffered from fragmentation or loss of functionality following adsorption on metal surfaces, with rare exceptions6–9. Robust metal–organic platforms, on the other hand, rely on external axial ligands to induce spin switching10–14. Here we integrate a spin switching functionality into robust complexes, relying on the mechanical movement of an axial ligand strapped to the porphyrin ring. Reversible interlocked switching of spin and coordination, induced by electron injection, is demonstrated on Ag(111) for this class of compounds. The stability of the two spin and coordination states of the molecules exceeds days at 4 K. The potential applications of this switching concept go beyond the spin functionality, and may turn out to be useful for controlling the catalytic activity of surfaces15. Spin-crossover complexes often lose their functionality upon adsorption on metal surfaces. Here, a metal–organic complex adsorbed on a silver surface undergoes reversible interlocked spin and coordination switching, which is enabled by an intramolecular feedback mechanism controlling the position of an axial ligand strapped to the complex.

Published
2020
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5. Magneto-Crystalline Anisotropy of Fe, Co and Ni slabs from Density Functional Theory and Tight-Binding models

Author

Cyrille Barreteau, Ludovic Le Laurent, Troel Markussen, Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Synopsys Denmark (Synopsys ), Synopsys Inc., European Project: 766726,211587,COSMICS(2017), Barreteau, Cyrille, Concepts and tools in molecular spintronics - COSMICS - 2017-11-01 - 2021-10-31 - 766726 - VALID, Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Condensed Matter - Materials Science, Work (thermodynamics), Materials science, Condensed matter physics, Plane wave, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, Space (mathematics), Magnetocrystalline anisotropy, 01 natural sciences, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Tight binding, 0103 physical sciences, Slab, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Density functional theory, 010306 general physics, 0210 nano-technology, Basis set
Abstract

International audience; We report magneto-crystalline anisotropy (MCA) calculations of Fe, Co and Ni slabs of various thicknesses and crystallographic orientations from two Density Functional Theory codes based either on a plane wave or a local atomic basis set expansion and a magnetic tight-binding method. We analyze the evolution of the MCA with the number of layers of the slabs. The decomposition of MCA into contributions of atomic sites helps understanding the oscillatory behaviour of the MCA with the slab thickness and highlights the role of finite size effects. We also identify some specific systems with enhanced MCA. A k-space as well as a band-filling analysis show very rich features of the MCA that could be used to tailor systems with enhanced magnetic properties. Finally this work can serve as a benchmark for MCA calculations.

Published
2019

6. Importance of Epitaxial Strain at a Spin-Crossover Molecule–Metal Interface

Author

Yannick J. Dappe, Talal Mallah, Cynthia Fourmental, Jérôme Lagoute, Cristian Enachescu, Cyrille Barreteau, Sourav Mondal, Shobhana Narasimhan, Marie-Laure Boillot, Rajdeep Banerjee, Sylvie Rousset, Alessandro Coati, Amandine Bellec, Yann Girard, Vincent Repain, Cyril Chacon, Alexander Smogunov, Yves Garreau, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Laboratoire de chimie inorganique (LCI), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Department of Solid State and Theoretical Physics, Alexandru Ioan Cuza University of Iași [Romania], Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Theoretical Sciences Unit, European Project: 766726,211587,COSMICS(2017), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Diffraction, Materials science, Spin states, Spintronics, 02 engineering and technology, Substrate (electronics), 010402 general chemistry, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, 0104 chemical sciences, Chemical physics, Spin crossover, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Molecule, General Materials Science, Physical and Theoretical Chemistry, 0210 nano-technology, Spin-½
Abstract

International audience; Spin-crossover molecules are very appealing for use in multifunctional spintronic devices because of their ability to switch between high-spin and low-spin states with external stimuli such as voltage and light. In actual devices, the molecules are deposited on a substrate, which can modify their properties. However, surprisingly little is known about such molecule–substrate effects. Here we show for the first time, by grazing incidence X-ray diffraction, that an FeII spin-crossover molecular layer displays a well-defined epitaxial relationship with a metal substrate. Then we show, by both density functional calculations and a mechanoelastic model, that the resulting epitaxial strain and the related internal pressure can induce a partial spin conversion at low temperatures, which has indeed been observed experimentally. Our results emphasize the importance of substrate-induced spin state transitions and raise the possibility of exploiting them.

Published
2019
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7. Fragmentation and Distortion of Terpyridine-Based Spin-Crossover Complexes on Au(111)

Author

Marcel Mayor, Gero D. Harzmann, Thomas Knaak, Manuel Gruber, César González, Thomas Brandl, Yannick J. Dappe, Richard Berndt, Christian-Albrechts-Universität zu Kiel (CAU), Universidad Autonoma de Madrid (UAM), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Basel (Unibas), Karlsruhe Institute of Technology (KIT), European Project: 766726,211587,COSMICS(2017), Universidad Autónoma de Madrid (UAM), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Materials science, Electrospray ionization, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, law.invention, Metal, chemistry.chemical_compound, Fragmentation (mass spectrometry), law, Spin crossover, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Physical and Theoretical Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Crystallography, General Energy, chemistry, visual_art, visual_art.visual_art_medium, Density functional theory, Condensed Matter::Strongly Correlated Electrons, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Scanning tunneling microscope, Terpyridine, 0210 nano-technology
Abstract

International audience; Spin-crossover complexes are attractive for their spin-switching functionality. However, only a few compounds have been found to remain intact in direct contact to metal surfaces. For the design of new spin-crossover complexes, it is important to understand the mechanisms leading to fragmentation. Here, we investigate, using low-temperature scanning tunneling microscopy along with density functional theory calculations, two Fe-(terpyridine) 2 complexes deposited on Au(111) by electro-spray ionization with in-line mass selection. Only fragments of the first compound are observed on the surface, while the second compound is strongly flattened. On the basis of a detailed analysis of the adsorbates on the surface, possible mechanisms for the fragmentation and molecular distortion are proposed.

Published
2019
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8. Spin in a closed‐shell organic molecule on a metal substrate generated by a sigmatropic reaction

Author

Richard Berndt, Nicolás Lorente, Marie-Laure Bocquet, Manuel Gruber, Ministerio de Economía y Competitividad (España), European Commission, Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640) (PASTEUR), Département de Chimie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universidad Pública de Navarra [Espagne] = Public University of Navarra (UPNA), Christian-Albrechts-Universität zu Kiel (CAU), European Project: 766726,211587,COSMICS(2017), Université Paris sciences et lettres (PSL), École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL)

Subjects
Materials science, Radical, Allene, Sigmatropy, 02 engineering and technology, Conjugated system, 010402 general chemistry, 01 natural sciences, Catalysis, law.invention, Delocalized electron, chemistry.chemical_compound, law, Metal surfaces, Moiety, Molecule, [CHIM]Chemical Sciences, Physics::Chemical Physics, Scanning tunneling microscopy, Open shell, General Chemistry, General Medicine, 021001 nanoscience & nanotechnology, 3. Good health, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Density functional calculations, chemistry, Organic radicals, Chemical physics, Scanning tunneling microscope, 0210 nano-technology
Abstract

Inert metal surfaces present more chances of hosting organic intact radicals than other substrates, but large amounts of delocalized electronic states favor charge transfer and thus spin quenching. Lowering the molecule-substrate interaction is a usual strategy to stabilize radicals on surfaces. In some works, thin insulating layers were introduced to provide a controllable degree of electronic decoupling. Recently, retinoid molecules adsorbed on gold have been manipulated with a scanning tunneling microscope (STM) to exhibit a localized spin, but calculations failed to find a radical derivative of the molecule on the surface. Now the formation of a neutral radical spatially localized in a tilted and lifted cyclic end of the molecule is presented. An allene moiety provokes a perpendicular tilt of the cyclic end relative to the rest of the conjugated chain, thus localizing the spin of the dehydrogenated allene in its lifted subpart. DFT calculations and STM manipulations give support to the proposed mechanism., M.‐L.B. thanks the national computational center CINES, and TGCC (Grant 2017‐ [GENCI project: A0010807364]) for a computer grant and acknowledges the Mercator fellowship of SFB 677 in CAU Kiel. N.L. acknowledges financial support from MINECO (MAT2015‐66888‐C3‐2‐R) and FEDER funds, and he is thankful to the Mercator fellowship of SFB 677 in CAU Kiel. M.G. acknowledges financial support of SFB 677. This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 766726.

Published
2019
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9. Experimental and theoretical investigations of magnetic anisotropy and magnetic hardening at molecule/ferromagnet interfaces

Author

C. Fourmental, Cyrille Barreteau, Yann Girard, L. Le Laurent, Jérôme Lagoute, Sylvie Rousset, Kaushik Bairagi, Cyril Chacon, Alexander Smogunov, Vincent Repain, Amandine Bellec, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Groupe Modélisation et Théorie (GMT), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Service de physique de l'état condensé (SPEC - UMR3680), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), European Project: 766726,211587,COSMICS(2017), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), and Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], Kerr effect, Materials science, Condensed matter physics, Magnetism, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter::Materials Science, Magnetization, Magnetic anisotropy, Ferromagnetism, Ab initio quantum chemistry methods, Magnet, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, 0210 nano-technology
Abstract

We measure by means of in situ magneto-optical Kerr effect the magnetism of ultrathin magnetic films supported on gold and platinum during the capping with molecular layers. We observe both for ${\mathrm{C}}_{60}$ and ${\mathrm{Alq}}_{3}$ molecules deposited on Co films an enhancement of the out-of-plane magnetic anisotropy, leading to a magnetic hardening for out-of-plane magnetization. Surprisingly, the amplitude of this hardening depends strongly on the underlying substrate. While we find an increase of the coercive field around 100% for Co/Au(111), it can reach almost 600% on Co/Pt(111). Those results are discussed by using both tight-binding and ab initio calculations. It is shown on the case of ${\mathrm{C}}_{60}$ that both the adsorption geometry and the strain in the magnetic layer can be key ingredients to predict the quantitative change of magnetic anisotropy induced by the interface between a magnetic material and a molecular layer. On the contrary, the crystalline stacking of the Co has a minor influence.

Published
2018
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10. Anomalous Light‐Induced Spin‐State Switching for Iron(II) Spin‐Crossover Molecules in Direct Contact with Metal Surfaces

Author

Massine Kelai, Sylvie Rousset, Cyril Chacon, Philippe Sainctavit, Edwige Otero, Luqiong Zhang, Vincent Repain, Amandine Bellec, Yongfeng Tong, Marie-Laure Boillot, M.-A. Arrio, Talal Mallah, Yann Girard, Eric Rivière, Jérôme Lagoute, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), European Project: 766726,211587,COSMICS(2017), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, Spin states, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, Molecular physics, 01 natural sciences, Catalysis, LIESST, Spin crossover, [CHIM.COOR]Chemical Sciences/Coordination chemistry, ComputingMilieux_MISCELLANEOUS, Valence (chemistry), 010405 organic chemistry, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, General Medicine, Photoelectric effect, 021001 nanoscience & nanotechnology, 0104 chemical sciences, X-ray Absorption Spectroscopy, Spin-Crossover, Molecule / metal interface, Excited state, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Condensed Matter::Strongly Correlated Electrons, Light induced transition, 0210 nano-technology, Excitation, Visible spectrum
Abstract

Light‐induced spin‐state switching is one of the most attractive properties of spin‐crossover materials. In bulk, low‐spin (LS) to high‐spin (HS) conversion via the light‐induced excited spin‐state trapping (LIESST) effect may be achieved with a visible light, while the HS‐to‐LS one (reverse‐LIESST) requires an excitation in the near‐infrared range. Now, it is shown that those phenomena are strongly modified at the interface with a metal. Indeed, an anomalous spin conversion is presented from HS state to LS state under blue light illumination for FeII spin‐crossover molecules that are in direct contact with metallic (111) single‐crystal surfaces (copper, silver, and gold). To interpret this anomalous spin‐state switching, a new mechanism is proposed for the spin conversion based on the light absorption by the substrate that can generate low energy valence photoelectrons promoting molecular vibrational excitations and subsequent spin‐state switching at the molecule–metal interface.

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